Use flink images from dockerhub

Hi @alpinegizmo,
thanks for sharing the project. I was asking my self why did you not used the flink images which are available https://hub.docker.com/_/flink?tab=tags&page=1&name=1.10.1 it would make the Dockerfile less verbose and also some of the build.sh less verbose. 

Do you see any concerns do use the provided images instead of downloading flink binaries in docker build step?